import pygame
from pygame.sprite import Sprite
import random
import alien_Images
class Alien(Sprite):
    # flag = False
    #表示单个外星人的类
    def __init__(self,ai_settings,screen):
        #初始化外星人并设置其起始位置
        super(Alien, self).__init__()
        self.screen = screen
        self.ai_settings = ai_settings
        #加载外星人图像，并设置其rect属性
        k = int(random.uniform(1, 4))
        # print(k)

        if k == alien_Images.Number_ONE:
            self.image = pygame.image.load(alien_Images.AlienImages_ONE)
        elif k == alien_Images.Number_TWO:
            self.image = pygame.image.load(alien_Images.AlienImages_TWO)
        elif k == alien_Images.Number_THREE:
            self.image = pygame.image.load(alien_Images.AlienImages_THREE)



        self.rect = self.image.get_rect()
 
        #每个外星人最初都在屏幕左上角附近
        self.rect.x = self.rect.width
        self.rect.y = self.rect.height
 
        #存储外星人的准确位置
        self.x = float(self.rect.x)
 
    def check_edges(self):
        #如果外星人位于屏幕边缘，就返回Ture
        screen_rect = self.screen.get_rect()
        if self.rect.right >= screen_rect.right:
            return True
        elif self.rect.left <= 0:
            return True
 
 
    def update(self):
        #向左或向右移动外星人
        self.x += (self.ai_settings.alien_speed_factor * self.ai_settings.fleet_direction)
        self.rect.x =self.x
 
    def blitme(self):
        #在指定位置绘制外星人
        self.screen.blit(self.image, self.rect)
